Hydrogen Production by Steam Dissociation using Oxygen Transport Membranes

Abstract

Hydrogen production via water splitting at 900{degree sign}C has been studied with mixed-conducting SrFeCo0.5Ox (SFC2) membranes. The hydrogen production rate increased with decreasing membrane thickness, but surface reaction kinetics began to dominate the behavior of thin (<1 mm) membranes without porous layers on their surface. Membranes coated with porous SFC2 layers, on the other hand, exhibited linear behavior up to an inverse thickness of ≈4 mm-1, and they yielded a higher hydrogen production rate than uncoated membranes with a similar thickness. To increase the hydrogen production rate, a thin film of SFC2 was fabricated by a colloidal casting method. The maximum hydrogen production rate of 17.4 cm3/min-cm2 was measured at 900{degree sign}C with a ≈20-µm-thick SFC2 film. The hydrogen production rate of the film, however, was significantly lower than the expected rate based on the membrane-thickness-dependence measurement because of concentration polarization and surface kinetic limitations.